It is well-known to use vegetable protein sources as a replacement for animal protein, including meat. This is widely used so as to provide the necessary proteins in a vegetarian diet. During the past decade, attention has increasingly emerged on reducing the consumption of meat. This has various backgrounds, depending on, e.g., the region of the world, including health benefits, meat scarcity, and social and environmental desires, such as animal welfare and reducing the effects of meat-production for the release of CO2 into the environment.
A major limitation to attempts to reduce the consumption of meat is the general acceptability of vegetable protein products as meat-replacements. In order for these products to be generally accepted, it is considered that such meat-replacement should actually resemble meat. Although many different products exist on the basis of, e.g., soy-bean protein that are claimed to resemble meat, these products to many consumers are still not sufficiently alike meat to really count as an acceptable replacement
The main route in the art in providing acceptable meat-replacements is to try and provide a meat-like fibrous structure. A further desire is to provide a process by which a range of meat-replacements can be produced on the basis of vegetable protein. For, it makes quite a difference whether the structure is produced as a replacement for minced meat, for chicken, pork steak, or for beef. A largely unmet desire is to provide a process that is capable of producing vegetable protein-based analogues of the more challenging meat structures, such as pork steak or beef. A particular further desire is to provide a process that is capable of being tuned towards the production of any one of a variety of meat replacements, ranging from minced meat to ham, chicken, or beef.
Several references address the production of fibrous, sometimes meat-like protein structures.
WO 03/07729 concerns a method of continuously preparing a retextured food product from a protein-rich raw material of animal and/or plant origin. In an extruder the raw material is subjected to mixing, cooking, and plasticizing steps, and cooled gradually in an extrusion die to a temperature that preferably is 40° C. to 80° C. In general products are obtained having a longitudinal fibrous structure. Such a structure is not generally acknowledged as being meat-like. To the extent that meat-like structures are suggested, this refers to a fibrous sheet structure. Whilst said to be a approximation of poultry meat, this is a relative simplification of such meat.
WO 2009/105654 relates to a protein composition for meat products or meat analogue products. The composition is granular, and is prepared by a process involving making a hard fibrous gel, and reducing the size thereof to particles of about 2 mm to 10 mm particle size. In some embodiments, granules are mixed with aligned protein fibres, and then chopped. The process of making the aligned protein fibres can be conducted by extrusion. To this end an extrusion die is used that serves to align fibres.
In any event, the resulting chopped structure does not resemble a fibrous muscle meat, and the process requiring fibre alignment results in a simplification of a meat structure. Moreover, the process does not provide the versatility to produce meat analogues ranging from minced meat analogues to steak analogues.
A general background reference on protein structuring is Cheftel et al., Food Reviews International 8(2), 235-275 (1992). Herein a protein texturization process is described, involving extrusion cooking at high moisture levels. The document relates to a broad range of products. E.g. it is described how fish proteins are restructured, how cheese-like products can be made, and how extrusion cooking can be used to create fat substitutes. It will be appreciated that the disclosed structures are not at all alike meat of land-animals.
The background art further includes US 4,276,319. Therein the production of a dense, granulated protein gel is disclosed which, upon rehydration, is to function as a meat extender in natural meat products. The disclosure does not provide a meat analogue of a meat-like structure that would be suitable per se as a meat replacement, rather than as an extender.
Yet another background reference is Kitabatake, Journal of Food Science vol. 50, 1985, pages 1260-1264. Therein the production of gels from soy protein isolate is disclosed. The disclosure is not directed to making meat-analogues, and the disclosed gels do not satisfy the corresponding texture requirements.